I'm the author of PtBi (which I am apparently not allowed to link to, it's at ptbi.metaclassofnil.com) and I (and some others in the program's tiny but dedicated user base) have been using Intensity Pro HW for years to play 720p60 games.

The Pro 4k looks like a perfect upgrade, but I wonder about the capture latency at 1080p60, as this is a huge issue with many existing cards for our use case. In particular, I'd like to know the average latency which can be expected from the HW, driver and API stack at 1080p60 until an application gets a frame from the API.

The Intensity Pro 4K uses the new architecture of the other Blackmagic Design cards announced in 2014 like SDI 4K and Studio 4K . The family of cards are real time full duplex meaning they can process input and output at same time. They also have much reduced latency. Overall Latencies are always dependent on the system and peripherals involved and measurement methodology.

To answer the question, once the input port has the video frame on the Intensity Pro 4K it should be no more than 1-2 frames latency into the system architecture and back to output if you are using our Blackmagic Design SDK for your development. If you need additional developer support -send PM.